Tuning material properties of organic surface modified titania: synthesis-property correlation
4 mei 2020
ONLINE - - - -- --
Organisatie / co-organisatie:
Jeroen Van Dijck
Vera Meynen en Anita Buekenhoudt
ONLINE Doctoraatsverdediging Jeroen Van Dijck - Faculteit Wetenschappen, Departement Chemie
Organic surface modified metal oxides are of great interest for the chemical due to their selective control of surface properties, triggering particular features and enhancing performance in applications. The most commonly used surface modification technique is organosilylation. Organosilylation of metal oxides is not ideal because the stability of the resulting organic layer is limited. Therefore, the search for more suitable surface modification techniques for metal oxides has gained significant interest over the past years.
Two promising alternatives are organophosphonic acid surface modification and Grignard surface modification. Organophosphonic acid modification is a condensation reaction between the organophosphonic acid and the surface hydroxyls of the metal oxides. Stable (sub)monolayers are grafted and the modification can be easily controlled by adjusting the reaction conditions. A drawback is that multiple bonding states exist, which could introduce side interactions. Moreover, it is often difficult to control the type and uniformity of these bonding states. Therefore, another alternative method has been developed by UAntwerpen and VITO: Grignard surface modification. It results in a direct bond between the organic functional group and the metal oxide surface, meaning that no reactive bonds of the precursors remain unbound on the surface. Grignard modification is not a condensation reaction and its exact mechanism is unclear. Therefore, unravelling this mechanism has been one of the key research questions of this PhD.
Both methods give rise to entirely new generations of organic modified metal oxides surfaces with unique physicochemical properties and behavior in application, that can be tailored to the application when the synthesis-properties and properties-performance correlations can be unraveled. While the impact of reaction conditions on the surface properties has been (partly) described for organophosphonic acid modification, the impact of these differences in surface properties on the affinity of the modified surface for molecular interactions has not been studied in-depth. For the Grignard surface modification insights in both the synthesis-properties and properties-performance correlations is missing due to the lack of understanding of the modification mechanism. It is for that reason, that this PhD has a particular attention on the one hand for unravelling part of the synthesis-properties correlation of Grignard modification on titania, by gaining a better understanding of the mechanism and the impact of reaction conditions, and on the other hand to study the impact of the synthesis on the sorption behavior of both Grignard and phosphonic acid modified surfaces.